The protection of a device by means of a device code is frequently used when, to prevent theft of the device, the latter should be equipped so that the theft is not worthwhile for a thief, since the stolen device is not operable. If the protection of certain devices by means of a device code is generally known, the number of thefts of these devices consequently decreases.
For example, the method is used for car radios, since a car radio can be easily removed by breaking into the car. Usually a PIN number is stored in the device and when the device is delivered, the customer is provided with this PIN number, for example, by means of a sticker on the operating instructions. Provided that the device and the PIN are kept in separate places, the device is thus inoperable and, consequently, it is of no interest to the thief. With car radios, the PIN number is required if a disconnection from the power system occurs or each time it is turned on.
Another means of preventing unauthorized use by means of a cell phone is known. In cell phones, a so-called SIM card is used by a cell phone supplier, without which the device cannot be operated. The SIM card is released by the cell phone supplier. However, this does not necessarily prevent the device from being stolen and used in conjunction with another SIM card.